1. Field of the Invention
The present invention relates to a power adapter for electrical installations and especially domestic installations with so-called "carrier current" control.
2. Description of the Prior Art
It is already known that the rates charged for electric service by power distribution utilities increase with the maximum power for which the user has applied under service contract. In view of this situation, it has been proposed to adopt units designated as "load-shedders" having one input connected to the output of the general circuit-breaker and a number of power outputs each connected to one or a number of power consumption points. When the consumption exceeds a predetermined threshold value which is slightly lower than the service contract power, the load-shedder automatically disconnects these power outputs in cascade in a predetermined order of priority until the power consumption is restored to the service contract level. Certain units of this type enable the user to program the level of priority of power outputs or in other words the order in which said outputs are disconnected in the event of threshold overshoot.
Another known form of rate schedule is the time-differentiated scale in which the kilowatt-hour price level varies according to the time of day or night, thus giving rise to the night-rate schedule. In another billing system at present in use, a reduced rate is applied on a year-round basis except for a few so-called "peak" days in which the tariff, or billing rate, is particularly high. In the system just mentioned, a warning signal is sent over the network a predetermined time before the high rate comes into effect, thus urging the user to moderate his power consumption. A second signal is then delivered in order to switch the meter to the new billing rate.
Co-pending U.S. patent application Ser. No. 877,759 filed by the present Applicant as joint owner on June 24, 1986 accordingly describes a power-adapting device which enables the user both to maintain a moderate maximum power level and to optimize his power consumption as a function of the prevailing rate charged.
In accordance with the patent application cited in the foregoing, the power adapter comprises a power input, a plurality of power outputs and a load-shedding device so designed that when the power consumption oversteps a predetermined threshold value, at least a certain number of power outputs ar disconnected in cascade in a pre-established order until said power consumption is restored to said threshold value and said power outputs are subsequently re-connected in the reverse order. The power adapter is essentially provided in addition with means for selectively assigning an erasure permission to at least a certain number of power outputs independently of the pre-established order aforesaid, and with erasing means responsive to a signal which is representative of the power cost, the outputs to which an erasure permission has been assigned being disconnected by said signal when the power cost is at a high value.
In accordance with U.S. patent application Ser. No. 877,759, orders for load-shedding on non-priority consumers are carried out directly at the level of the power adapter. When an adapter of this type is fitted in an existing domestic installation, the outgoing lines for supplying current to sheddable equipment units (or in other words non-priority units) must therefore be separately and distinctly available, for example on a distribution panel, in order to ensure that they can be readily connected to the outputs of the adapter without having to proceed to a complete rearrangement of the electric wiring system of the installation.
In most domestic electrical installations, however, no provision is made for any distribution panel of the type just mentioned. Only a single supply line is led out from the circuit-breaker to supply a number of appliances in parallel. In order to include the above-mentioned power adapter in this type of installation, it is consequently necessary to carry out a practically total reorganization of the electrical system and this carries a heavy cost penalty in the majority of instances.
The object of the present invention is to propose a power adapter which exactly satisfies the same functions as the adapter described in the patent application cited earlier while offering the same advantages and permitting integration in an existing installation without any need for extensive wiring operations.